<!DOCTYPE html>
<html>
<head>
  <title>随机数生成器</title>
  <style>
    body {
      display: flex;
      justify-content: center;
      align-items: center;
      height: 100vh;
      margin: 0;
    }
    
    h1 {
      font-size: 48px;
    }
  </style>
</head>
<body>
  <h1 id="randomNumber"></h1>

  <script>
    // 生成1-20之间的随机数
    var randomNumber = Math.floor(Math.random() * 20) + 1;

    // 将随机数显示在页面上
    document.getElementById("randomNumber").innerText = randomNumber;
  </script>
</body>
</html>
